How many firearms can I sell before I need an FFL   

There is no hard number of guns you can sell before needing an FFL, but frequent sales or selling for profit could trigger ATF scrutiny. If in doubt, it’s best to consult with an FFL dealer or attorney to ensure compliance with federal and state laws.

How many firearms can I sell before I need an FFL?
If I sell someone a gun without running a background check, and they uses it to commit a crime, can I be held responsible?
Am I responsible for legally selling a firearm to a legal purchaser? What I mean is, if I sell my gun to a local gun shop, am I held accountable for that gun forever if I am the original legal buyer?
Can you sell a gun without an FFL? Do I need an FFL to own a gun? Is it illegal to sell guns privately? How many guns can you sell per year? How to legally sell a gun online ? Can you sell a gun without an FFL? Do I need an FFL to own a gun? Is it illegal to sell guns privately?

https://medium.com/@juicefruit420/firearms-2025-trends-online-f3a9e2f0f07a
https://medium.com/@juicefruit420/firearms-gun-auctions-live-auction-world-b7f9eee740ae
https://crypto-potential.com/post/government-gun-auction-online